A gas-test device of the type used, for example, as a so-called breathalyzer to test the alcohol content of the exhalations of a drunk-driving suspect normally comprises a glass tube defining a fluid-flow passage in which is provided a mass of particles that, when they react to the alcohol component of a stream of gas passing through them, change color. In the standard drunkometer test the suspect is required to inflate a balloon, thereby passing a measured volume of his or her exhalations through the test cartridge to determine the alcohol level in the volume of gas held by the balloon.
A problem with such devices is that the cartridge containing the reactive material must be kept in a sealed environment and only at the last minute is fitted to the mouthpiece of the balloon to run the test. Any minor difficulties make the test invalid so that handling of the delicate cartridge must be minimized.
Another problem with the known devices is that the crystals that hold the reactive substance get powdered by rough handling so that they no longer work properly.